Many buildings heating systems, especially residential buildings heating systems, use a primary heating system which comprises a forced air furnace for heating and cooling. Air is heated by the forced air furnace and dispersed throughout the building through ducting. While there are many advantages and reasons for using a forced air furnace as the primary heating system in a building, there are some applications where it is desirable to have in addition to the forced air heating, a radiant heating system using circulating heating fluid for specialized heating, that cannot be achieved with a forced air furnace alone.
Additionally, using forced air heating alone often involves some disadvantages. A common disadvantage of using a forced air furnace alone is that the heated air in a room, because it has a tendency to rise, can often leave the floor of the room cooler than the surrounding air. This problem is further exaggerated when the building comprises multiple floors, such as a main floor and a basement. The thermostat for the forced air furnace is typically on a main level with the result that the main level is often comfortable, but the lower levels, such as the basement are somewhat cooler than the main level. Basements also typically have ceiling diffusers that are used to supply the heated air to spaces, which further exaggerates the problems with the heated air in a room tending to rise because the ceiling diffusers introduce the heated air into the basement space at ceiling level.
Often these disadvantages and/or problems can be addressed with the use of a secondary radiant heating system that uses circulated heating fluid. These radiant heating systems provide heat by having heated fluid circulated through them in a series of conduits or a heating loop. Heat from the heating fluid circulating through the radiant heating loop is radiated to the surrounding area and heats the surrounding area. For example, if a radiant heating system in the form of an in-floor heating system is used in the basement, the floor in the basement is warmed by the radiant heating system and can maintain the basement space at a much more comfortable temperature than just using the forced air system alone.
The disadvantage of using a secondary radiant heating system that operates using circulating heating fluid is that there must be a heat source for heating the heating fluid to be circulated through the radiant heating system. Typically, in the prior art systems a boiler system is installed, which is completely separate and is additional to the forced air furnace, which is used as the primary heating system for the building. This boiler is then used to heat the heating fluid to be circulated through the radiant heating system. The disadvantage of using a boiler is that boilers are more complex to design, operate and maintain than forced air furnaces. Additionally, there is the added expense of the boiler which is purchased in addition to the forced air furnace that will be used as the primary source of heating, cooling and ventilation that may be already in place.